"When everything weighs the same, nothing weighs anything."

Easily the most popular book ever written about naked young boys playing laser tag in space, Orson Scott Card’s “Ender’s Game” has been a sci-fi mainstay since its first publication in 1985. Since it took 28 years to get it to the big screen, the fact that the end result feels rushed and hasty probably qualifies as irony.

Not in terms of production value, mind you. Adapted and directed by Gavin Hood (“Tsotsi,” “X-Men Origins: Wolverine”), this “Ender’s Game” is about as slick a spectacle as fans could have hoped for, blending futuristic wonderment with recognizable human behavior. The zero-gravity capture-the-flag games are convincing (and fun), and the various spacecraft involved are rendered with crispness and clarity. This sucker was obviously not just slapped together.

It’s the storytelling that feels hurried. In the future, some 50 years after an insectoid race of aliens attacked Earth and killed millions, our hero, Ender Wiggin (Asa Butterfield), is one of many pre-teen boys (and a few girls) who have enlisted in the international military academy. The training facilities are on a space station orbiting the Earth, and the technology is advanced, but otherwise it’s not much different from a prep school or a Hogwarts.

Before the movie even starts, overseers Col. Graff (Harrison Ford) and Maj. Anderson (Viola Davis) have detected great potential in Ender. In a matter of minutes, they’ve determined that his willingness to keep kicking an already-defeated bully is evidence of his suitability for military command. Shortly after that, they’re fast-tracking him for battle training. Graff goes out of his way to praise Ender’s intelligence and skill in front of the other kids so they’ll resent and challenge him.

Ender does indeed rise quickly in the ranks, showing a skill for strategy in the war games that he and his fellow cadets practice day in and day out. He outfoxes his jealous team leader, the delightfully named Bonzo Madrid (Moises Arias), and bonds with female recruit Petra Arkanian (Hailee Steinfeld). His other friends, Bean (Aramis Knight) and Alai (Suraj Partha), are present but under-utilized, while his family members back on Earth hardly get any screen time at all.

Just what it is about Ender that makes the higher-ups so sure he’ll be their savior remains a mystery, both to him and to us. Yes, he’s smart — but surely the army has had smart leaders before. (One of them, played by Ben Kingsley, appears later.) Why are we putting all our eggs in the Ender Wiggin basket? That’s the sort of thing that might be addressed if the movie weren’t constantly chugging from one plot point to the next, rarely stopping to explore or ponder. Elements that were critical to the book (like the “mind games” Ender plays, the dreams he has, and his relationship with his siblings) are glossed over or omitted so the movie will have time to hit the required story beats — never mind that those story beats don’t mean anything if the film doesn’t help us understand why they’re happening.

Dodgy American accent aside, Asa Butterfield (from “Hugo”) acquits himself well enough in the lead role, as does the rest of the young cast. Harrison Ford seems to be awake and paying attention, and Viola Davis adds crucial gravitas to her few scenes as a sympathetic officer. By all appearances, this should be an excellent sci-fi adventure. But Hood keeps such a steady, unvaried pace that the revelations of the final act — which should be HUGE — have the same dramatic heft as everything else. And when everything weighs the same, nothing weighs anything.